[Ron Ramirez]

Stude - There are two versions of the 37-11; 9,400 of the second version (which you now have) were made. 5,900 of the first version were made.

According the the Service Bulletin for Model 37-11, which also covers Model 37-10, the only difference between the two is in the 2nd detector-1st audio circuit. Model 37-10 has a 6Q7G performing both functions. Model 37-11 has a 6J5 second detector, connected as a dual diode (the grid is used as one of the diode "plates"); and a 6K5G is the 1st audio amp.

Philco would pull this trick several times in later years; having a lesser model using one tube as 2nd detector and 1st audio, and a higher priced model using two tubes for these functions. Some examples include Models 39-25 and 39-30; 40-150 and 40-155; 40-180 and 40-185/190; 40-195 and 40-200/201; 41-250 and 41-255; 41-280 and 41-285/287; 41-295 and 41-300/315.